ENCHYTR^ID^ 



9 



cles are surrounded by circular muscles in the immediate vicinity of 

 the sperm-duct. In other species these circular muscles are wanting. 

 If we follow these fine hair-ducts of the cells we find that some of 

 them after having penetrated the muscular coat of the sperm-duct, 

 enter between the inner epithelial cells of the atrium, and empty their 

 contents into the atrial lumen. Other ducts again do not open into the 

 lumen at once, but run either up or down between the epithelium of 

 the atrium and its muscular layers, and only enter the atrial lumen a 

 considerable distance from the place where they penetrated the atrial 

 covering. In many species the glandular ducts form a thick layer of 

 fine thread-like ducts, which layer is thicker than any of the atrial layers 

 proper. While some of the ducts from the glands enter the atrial 

 lumen without being enlarged or widened out, others first widen out, 

 forming a small pocket in which their granular contents are stored. 

 The number and location of the atrial glandular fascicles vary in dif- 

 ferent species. In some instances they penetrate the atrium in the 

 same equatorial plane, while in other species they cover the atrium in 

 an irregular manner. In some species these fine ducts of the cells 

 continue downward in the atrium but open only at the penial pore on 

 the surface of the body-wall. In some species the atrial glands are 

 wanting, while in others they seem to be replaced by minute glands 

 situated entirely inside the atrium near the penial pore. 



Another set of glands connected with the spermiducal organ consist 

 of accessory glands, which open near the penial pore, but which stand 

 in no connection with either the sperm-duct or the penial bulb. In 

 some species there are many accessory glands arranged in a ring in the 

 coelomic cavity around the bulb and opening along a circular band 

 around the penial pore. But in other species there may be only two 

 or even one single fascicle of accessory glands opening in a pore by 

 itself, but in the immediate vicinity of the penial pore. In structure 

 these glands resemble the atrial and penial glands (figs. lo, 32). The 

 exterior pore of these accessory glands is often very large, reminding 

 us of the tubercula pubertatis in the higher Oligochaeta. 



At the lower end of the sperm-duct we find in many species, both of 

 Mesenchytrceus and Ltimbricillus^ etc., a set of very small glands wliich 

 appear to open directly in the sperm-duct. These glands are often 

 enclosed within the muscles of the sperm-duct, and appear as an en- 

 largement of the duct. But it is to be noted that the surface on which 

 these glands open is destitute of any epithelial cells, those of the 

 sperm-duct always ending where the glands commence. I have, there- 

 fore, referred to these glands as opening in the prolongation of the 



